JP2017534821A - Built-in, energy efficient hydraulic actuator system - Google Patents

Abstract

The built-in and energy efficient hydraulic actuator system of the present invention is configured to generate a rated torque of maximum rated RPM from zero RPM with a hydraulic cylinder and rotor speed / position feedback to the servo motor. Servo motor, pump, and solenoid valve that allows the hydraulic cylinder to maintain its position without operating the motor. The system has the ability to use a solenoid valve to hold the load in place without motor operation, thus conserving energy and extending motor life by minimizing motor run time.

Description

  This application is a U.S. application 14 / 511,463, filed October 10, 2014, entitled “Self-Contained Energy Efficient Hydraulic Actuator System”, which is incorporated herein by reference in its entirety. Claim its priority based on the description.

  The invention disclosed and taught herein relates generally to self-contained actuator systems and, in particular, to self-contained and energy efficient hydraulic actuator systems.

  An actuator is a mechanism by which a control system acts on the environment. Actuators are typically operated by an energy source, such as an electric current, a motor, hydraulic fluid pressure, or pneumatic pressure, and convert that energy into motion.

  A hydraulic actuator typically consists of a cylinder that uses hydraulic power to facilitate mechanical operation. Mechanical motion produces output as linear, rotational or vibrational motion. The hydraulic cylinder consists of a hollow cylindrical tube on which the piston can slide. The term double action is used when pressure is applied to both sides of the piston. The pressure difference between the two sides of the piston results in movement of the piston to either side. The term single acting is used when fluid pressure is applied to only one side of the piston. If the piston simply moves in one direction, a spring is often used to give the piston a return stroke.

  Conventionally, hydraulic linear actuators are connected to a remote source of pressurized hydraulic fluid through a closed pipe network and control valves. However, the hydraulic linear actuator can be moved independently, and the prime mover, hydraulic pump, and closed hydraulic fluid control system are all integrated into the linear actuator and installed close to the linear actuator. There are desirable applications. Such compact and independent actuators are particularly suitable for industrial valve applications and remote locations where such valves can be installed.

  Prior art independent hydraulic actuators are disclosed in McLeod US Pat. Nos. 2,640,323 and 2,640,426, and Scanderbeg et al. US Pat. No. 5,144,801. Ramsey et al., US Pat. No. 8,336,613, and Silva et al. US Pat. No. 6,892,534.

  A self-contained hydraulic actuator system having a closed hydraulic system can incorporate a servo valve. The servo valve changes the direction of the fluid in the system and thus controls the movement of the double acting hydraulic cylinder. One of the disadvantages of using a servo valve to change the direction of fluid is the continuous internal leakage of the servo valve, which requires a continuous supply of hydraulic fluid from a prime mover driven pump. is there. A hydraulic servo valve may not function due to particle contamination, which may be carried into a tight gap between the moving components of the servo valve.

  A self-contained hydraulic actuator system can also incorporate a hydraulic pump (eg, a bidirectional hydraulic pump). These systems require a bi-directional motor that drives the hydraulic pump. The motion of the double acting hydraulic cylinder is controlled by the speed and direction of the hydraulic pump as fluid flows through the system.

  US Patent Application Publication No. 2007/0101711 to Debus discloses the use of an AC induction motor driven by a variable frequency drive (VFD), the speed and direction of the hydraulic pump being Controlled by. However, VFD drive motors have limited torque available at low RPM, cannot start under load, and resist rapid RPM changes and direction changes. The Debus application discloses the use of a bypass leak path that allows the motor to run at some minimum RPM when the actuator is stationary, but there is no separate provision for load locking, so the motor Requires continuous operation even in the holding position. The continuous operation of the motor results in unnecessary energy consumption, reduced motor life, frequent repairs, and ultimately extra costs.

  Arbel U.S. Pat. No. 7,640,736 describes a hydraulic linear actuator system that includes a pump configured to rotate in a single direction at a substantially constant speed. Arbel uses a unidirectional motor and a bidirectional stepper motor to change the direction of the pump and fluid flow. Both fluid direction and flow rate are controlled by adjusting the positional relationship between the pump stator and rotor. However, Arbel cannot provide for load locks. Another disadvantage of Arbel is that both the pump and the prime mover must be operated to maintain the actuator's stationary position.

  Scanderbeg et al., US Pat. No. 5,144,801, discloses an independent electro-hydraulic actuator in which an electric motor is disposed in a hydraulic fluid reservoir and connected to drive a hydraulic fluid pump. Is disclosed. Scanderbeg discloses that an electric motor drives a hydraulic pump “on demand (on demand)”. On-demand basis refers to the fact that the motor speed changes the “generation of only the required pressure and flow” but does not repeat on and off. When the actuator reaches the desired position, the motor decelerates but continues to run slowly to maintain the position. Scanderberg cannot provide a separate provision for load locking.

  Duff US Pat. No. RE39,158 discloses a hydraulic system manifold having a body, a counterweight in the body, and a flow controller in the body. The Duff patent is directed to an actuator that provides load locking through the use of a manifold having a counterweight and a mechanical outflow lock valve without the use of a motor. The Duff outflow lock valve operates at system or line pressure and holds the actuator in place when the motor is off. However, the pilot operated backflow prevention valve introduces a positioning resolution problem. Glomeau U.S. Pat. No. 4,766,728 is a disclosure of a flow matching valve that overcomes the positioning resolution problem of a pilot operated check valve.

  There are several drawbacks associated with the disclosure in the prior art. One important drawback is that the holding capacity of the actuator depends entirely on the continuous operation of the prime mover or mechanical control valve that locks the amount of fluid in the hydraulic cylinder. Traditional independent hydraulic linear actuators typically do not have the requisite motor, pump, and / or valve configurations to accomplish the load lock task and thus maintain fluid pressure for load lock Depends on the prime mover to do. This increases power consumption and reduces component life as the prime mover and pump need to operate continuously.

  Another important drawback is that the prime mover and pump frequently operate continuously in some applications to compensate for the servo valve leakage rate. This greatly limits the frequency response and position adjustment accuracy and reproducibility of the actuator.

U.S. Pat. No. 2,640,323 US Pat. No. 2,640,426 US Pat. No. 5,144,801 US Pat. No. 8,336,613 US Pat. No. 6,892,534 US Patent Application Publication No. 2007/0101711 US Pat. No. 7,640,736 US Patent RE39,158 U.S. Pat. No. 4,766,728

  Thus, in the art, an energy efficient actuator system that can operate in any orientation and enables load locking without the need for a servo valve, stopping the motor when the piston is stationary, There is a need to provide a system that has the ability to restart a motor from zero RPM under load.

  The present disclosure is directed to a built-in, energy efficient hydraulic actuator system. The prime mover (motor), hydraulic reservoir, and all other hydraulic components are all integrated together to form a hydraulic power source (HPS). The system utilizes at least one solenoid valve, preferably two solenoid valves, in an inventive manner to hold the load in place without motor operation. In particular, the present invention provides a bidirectional hydraulic pump that is operatively connected to a servomotor. Along with the hydraulic pump / servo motor and solenoid valve, the controller performs the flow operation in sequence. The servo motor and bi-directional hydraulic pump operate accordingly to control fluid flow and direction, while the solenoid valve performs the locking function of the actuator system.

  According to the present invention, the resulting actuator speed is a function of the displacement of the hydraulic pump and the displacement of the hydraulic cylinder.

  In a first embodiment, the disclosed self-contained and energy efficient hydraulic actuator system provides at least one piston and fluid communication with the piston to provide hydraulic fluid to the piston and control the position of the piston. At least one bidirectional hydraulic pump. At least one hydraulic fluid inlet, at least one hydraulic fluid outlet, and a servomotor operably connected to the pump to drive the pump, the at least one solenoid valve being a piston and a bi-directional pump Bi-directional hydraulic pump configured to control hydraulic fluid between. An actuator system having a controller (controller unit) for controlling the solenoid valve and the servo motor so that the position of the piston can be maintained when the servo motor does not drive the pump.

  Preferably, the hydraulic cylinder has a double rod end type piston, thereby minimizing the volume difference that is displaced when the piston moves in either direction in the cylinder. A uniform annular area or chamber is formed in the hydraulic cylinder.

  According to another preferred embodiment, the bidirectional hydraulic pump in the first preferred embodiment is a reversible gear pump.

  According to another preferred embodiment, a smooth or non-pulsating output from a bi-directional hydraulic pump is required.

  According to yet another preferred embodiment, the solenoid valve in the first preferred embodiment is configured to hold a load without operating the servo motor.

  According to yet another preferred embodiment, the servo motor in the first preferred embodiment is an AC brushless permanent magnet motor.

  According to yet another preferred embodiment, the controller in the first preferred embodiment comprises the servo motor feedback unit of the servo motor, the solenoid valve, and the position of the actuator / piston / rod and hydraulic cylinder attached to the hydraulic cylinder. The position sensor configured to detect the control device includes a control electronics unit and a servo drive unit configured to transmit and receive control signals.

  According to yet another preferred embodiment, the first preferred embodiment further includes a sealed reservoir configured to compensate for volume changes due to hydraulic fluid and system thermal expansion and contraction.

  According to yet another embodiment, the present invention provides a method for reducing energy consumption of a hydraulic actuator system having a servo motor and at least one solenoid valve. The method includes receiving at the controller an input signal corresponding to a desired operation of the function of the system, determining an operating limit (ie, actuator / piston / rod position) for the system by the controller, a servo motor, and Simultaneously controlling solenoid valves at operating limits. The hydraulic actuator system of the method includes at least one piston and at least one bi-directional hydraulic pump in fluid communication with the piston to provide hydraulic fluid to the piston and control the position of the piston, A pump having one hydraulic fluid inlet and at least one hydraulic fluid outlet; a servomotor operably connected to the pump to drive the pump; and a hydraulic pressure between the piston and the bidirectional pump At least one solenoid valve configured to control fluid, wherein the controller controls the solenoid valve and the servomotor, and maintains the position of the piston when the servomotor is not driving the pump. it can.

  A book that includes the ability to use a solenoid valve to hold a load in place without servomotor operation, the ability to generate torque from zero RPM to maximum RPM, and the ability to start from zero RPM under load It will be appreciated that several advantages of the present invention are achieved and reached by the inventive hydraulic actuator system. In particular, at zero RPM, the servo motor does not use energy, resulting in energy savings and extended servo motor life, while minimizing servo motor operating time. The actuator of the present invention can further change RPM and direction quickly and continuously without duty cycle limitations.

  Another advantage of the present invention is that hydraulic fluid pressure is reduced by adjusting the power input to the hydraulic pump by controlling prime mover (ie, servo motor) power, thus eliminating the need for mechanical pressure regulation. It is the ability to control.

  Another advantage of the present invention is that the output speed of the actuator is electrically controlled by a variable speed servomotor. This allows variable acceleration, speed, and deceleration to optimize performance for each individual application.

  Another advantage is the low energy consumption and long life of the prime mover (ie, servo motor) that operates only when the actuator is moving, because the speed of the servo motor is proportional to the required actuator motion.

The invention will now be described by way of example only with reference to the accompanying drawings.
1 is a schematic diagram of a preferred embodiment of a built-in, energy efficient hydraulic actuator system. FIG. FIG. 6 is a schematic diagram of another preferred embodiment of a built-in, energy efficient hydraulic actuator system.

  The present invention is a self-contained, energy efficient hydraulic actuator system 100 having a servo motor 4 and a bi-directional hydraulic pump 1, which pump assembly is responsive to the speed and direction of fluid flow through the system, as well as fluid flow. It can be adjusted to control the hydraulic cylinder 2 that responds.

  The present invention comprises at least one actuator, i.e. piston 14 and rod 15, via a first cylinder port 12 (inlet) and a second cylinder port 13 (inlet) for inflow or outflow of hydraulic fluid. A hydraulic cylinder 2 having at least one hydraulic fluid input and at least one hydraulic fluid output, in fluid communication with the hydraulic cylinder 2, providing hydraulic fluid to the hydraulic cylinder 2, At least one bidirectional hydraulic pump 1 for controlling the position, a servo motor 4 operatively connected to the bidirectional hydraulic pump 1 for driving the hydraulic pump 1, and for controlling the hydraulic actuator system 100 A hydraulic system including a controller unit 6 is provided. The output and speed of the actuator are electrically controlled by the control electronic circuit unit 6A of the controller unit 6 changing the speed of the servo motor 4 via the servo drive unit 6B. This allows variable acceleration, speed, and deceleration to optimize performance for each individual application.

  The bidirectional hydraulic pump 1 and the servo motor 4 are connected directly and continuously. A smooth or non-pulsating output from the bidirectional pump 1 is preferred. In this regard, piston type pumps will be problematic due to pressure / flow pulses. It is a one-to-one connection ratio which means that the RPM and direction of the bidirectional hydraulic pump 1 are always equal to the RPM and direction of the servo motor. The hydraulic actuator system 100 can use different sized servo motors and bi-directional hydraulic pumps with various displacements. For example, servo motors having rated horsepower of 0.25, 0.81, and 1.64 hp, and rated torques of 3.9, 12.77, and 25.87 inch-pounds, respectively. Examples of bi-directional hydraulic pumps that are useful in the motors described above include those having displacements of 0.0098, 0.0321, and 0.065 cubic inches per revolution, respectively. The servo motor 4 and the hydraulic pump 1 do not necessarily require a connecting gear or transmission, but can be adapted as needed.

  The hydraulic fluid pressure is controlled or limited by adjusting the power input to the bidirectional hydraulic pump 2 by controlling the power of the servo motor 4. The bi-directional hydraulic pump 1 has at least two ports, a first port 8 and a second port 9, for fluid flow in either direction through the port (for hydraulic fluid outflow or inflow). Can be pumped out. The bidirectional hydraulic pump 1 is operably connected to the hydraulic cylinder 2. When the bi-directional hydraulic pump 1 pumps hydraulic fluid, the hydraulic fluid drives the piston 14 and rod 15 of the hydraulic cylinder 2 to change the pressure differential, thereby moving and position of the hydraulic actuator system 100. To control.

  As used herein, servo motor 4 includes any motor that responds to a control signal by changing its speed or other operating parameter. According to the present invention, the servo motor 4 is used to control the bidirectional hydraulic pump 1. Servo motor 4 has the ability to reverse direction, change speed and maintain constant RPM instantaneously and continuously. The servo motor 4 is configured to generate a rated torque of maximum rated RPM from zero RPM under load.

  As used herein, the controller unit 6 includes a control electronic circuit unit 6A and a servo drive unit 6B, and monitors a position feedback signal from a position sensor 22 installed on the hydraulic cylinder 2 and is expected. Continuously adjust the deviation from the behavior. Many types of devices can be envisioned for use as the position sensor 22. For example, a potentiometer can be used as the position sensor 22. The servo drive unit 6B is used to operate the servo motor 4, and maintains the motor RPM under the situation where the load increases and the situation where the load exceeds, and uses a signal between the servo motor feedback unit 5 and the servo drive unit 6B. Thus, the closed loop control of the position and direction of the rotor of the servo motor and the speed of the servo motor is realized. The servo motor rotor, that is, the entire rotation portion of the servo motor including the output shaft attached to the bidirectional hydraulic pump 1. The servo motor feedback unit 5 of the servo motor 4 uses a digital encoder to provide feedback of the rotor speed, direction, and position to the servo drive unit 6B. The digital encoder (not shown) is a digital device in the servo motor feedback unit 5 that is connected to the end of the rotor of the servo motor 4. The digital encoder provides the servo drive unit 6B with feedback of servo motor speed, direction, and angular position of the rotor. However, the present hydraulic actuator system 100 does not necessarily require the angular position portion of the rotor feedback information, and only requires the rotor speed and direction to operate. Servo motor feedback unit 5, control electronics unit 6A, and servo drive unit 6B ensure accurate RPM control under variable load conditions. The hydraulic fluid pressure is controlled or limited by adjusting the power input to the servo motor 4 connected to the hydraulic pump 1, thereby requiring either a mechanical pressure regulator or accumulator. Disappears. An accumulator is a stored energy device that stores hydraulic fluid under pressure, such as a hydraulic storage battery. According to the present invention, the accumulator can be used for an emergency shutdown (ESD) condition, but is not required for normal operation. It means that the hydraulic actuator system 100 can utilize the accumulated energy of the accumulator to position its valve or device to a specified position under certain circumstances, such as loss of power.

  The bidirectional hydraulic pump 1 and the servo motor 4 combine to function as a servo valve, and control the fluid flow velocity and direction. As a result, the need for a servo valve is eliminated.

  As used herein, the solenoid valve 3 is an electromechanically operated valve. The solenoid valve 3 is controlled by a current passing through the solenoid. Use of the solenoid valve 3 allows the actuator system to hold the load in place without the servo motor 4 operating and to eliminate the need to operate the servo motor 4 to maintain the position. .

  The servo motor 4 / hydraulic pump 1 starts in a few milliseconds before the solenoid valve 3 is activated / opened. This timing and ordering is performed so that the pressure on the rear side of the solenoid valve 3 is equal to the load side so that there is no momentary reverse movement.

  In addition, the presently claimed actuator has dual mode (or duo mode) capability by maintaining the position relative to the load by using a solenoid valve, or by maintaining the position without using any valve. ) Can work in motion. The position of the first mode is held by a hydraulic lock created in the hydraulic cylinder 2 when the solenoid valve is closed. In the second mode of operation, the position is maintained by controlling only the speed of the prime mover (ie servo motor) 4 / hydraulic pump 1. In the second mode, the servo motor 4 / hydraulic pump 1 rotates only at a speed necessary to push away the internal leakage of the hydraulic pump 1. However, the exact pressure required to maintain position is maintained with zero fluid flow to and from the actuator cylinder in the first mode. The frequency response and position adjustment resolution of the actuator are not limited by the response time of the solenoid valve 3 and the minimum fluid flow per response.

  Because the solenoid valve is a mechanical device, there is a delay or delay when the solenoid valve 3 actually moves or opens from when an electrical signal is sent to the solenoid valve 3. This is mainly due to the physical inertia of the mechanical parts. Although the delay period is very short, i.e. milliseconds, the delay will still affect how quickly the actuator can respond to changes in the control signal.

  The frequency response is a measure of how many changes the hydraulic actuator system 100 can respond to during a given period, which is typically measured in seconds, ie cycles / second or hertz. The less time the solenoid action is delayed or the time spent waiting for the solenoid action, the more variable the actuator movement during a given period, or a faster frequency response is possible.

  The resolution is determined by the minimum amount of fluid that the actuator can pass with a given input signal change. Since the solenoid valve 3 has a delay time to open and a delay time to close, there is a minimum period during which fluid can flow through the solenoid valve 3. This minimum amount of fluid determines the minimum amount of actuator movement or resolution when using the solenoid valve 3. By not closing or using the valve, its limitations on resolution and frequency response are eliminated. Thus, the controller unit 6 uses or does not use the solenoid valve 3 depending on the frequency of change of the input signal.

  According to the present invention, the sequence of operations is as follows. Start with the resting hydraulic actuator system 100. The control electronics unit 6A of the controller unit 6 is represented by a value relative to that of the input control signal (4-20 mA from a remote source, ie plant control room (not shown)) transmitted to the controller unit 6. An internal comparator device (not shown) for continuously comparing the position of the rod 15 / piston 14 in the hydraulic cylinder 2 by means of the position sensor feedback signal 22A of the position sensor 22. When the input control signal changes and differs from the position sensor feedback signal 22A by an amount larger than the allowable deviation (exceeds the dead zone), the control electronic circuit unit 6A of the controller unit 6 moves the servo motor 4 in a specific direction. The control electronic circuit signal 6C to the servo motor feedback unit 5 that starts moving is started. Based on changes in the magnitude and direction of the input control signal and the position sensor feedback signal 22A, the control electronic circuit unit 6A first determines the speed and direction of the servo motor 4, that is, the “operation speed”.

  Secondly, the control electronic circuit unit 6A transmits a control electronic circuit signal 6D that opens the solenoid valve 3 in order to realize equalization of pressure.

  Third, the solenoid valve 3 opens and within a fraction of a second, ie substantially simultaneously, the servo motor 4 ramps up to the previously determined operating speed. The rod 15 / piston 14 now moves to their newly commanded position and the rod 15 is within 5 percent of the new position target of the rod 15 as measured by the position sensor 22 attached to the hydraulic cylinder 2. Then, the position sensor provides the position sensor feedback signal 22A to the control electronic circuit unit 6A, and the control electronic circuit unit 6A transmits the control electronic circuit signal 6C to the servo motor feedback unit 5, and therefore to the servo motor 4. Signal and start ramping down. When the commanded position is reached, the actuator overcomes the internal leakage of the hydraulic pump 1 and operates the motor 4 / hydraulic pump 1 just fast enough to maintain the pressure in the hydraulic cylinder 2 ( The position is maintained by servo control at a very low RPM) while the solenoid valve 3 remains open. This is done during an adjustable period. Alternatively, in the inventive process of the present invention, the servo motor 4 is turned off when a new position is achieved and the adjustable time constant of the solenoid valve 3 is satisfied. The speed of the servomotor 4 ramps down from the maximum travel speed to the “lock” speed during the last “5 percent” of the movement of the rod 15. The ramping process is primarily there to avoid overshooting of positions that are difficult to control when the motor runs to the new position at full speed and then simply shuts off.

  If the input control signal exceeds the adjustable period, i.e., the adjustable time constant, and remains in the dead zone of the new position, the solenoid valve 3 is closed and the RPM of the servo motor 4 is zero. The hydraulic actuator system 100 pauses again after waiting for a new input control signal change, i.e. a motion command. This adjustable time constant allows the actuator to have a continuous input control signal because the hydraulic actuator system 100 does not have to wait for the response time when the solenoid valve 3 opens or the pressure equalization before the solenoid 3 opens. It becomes possible to respond faster than the change of. This increases the frequency response of the actuator for a continuously modulating application. The control electronics unit 6A of the controller unit 6 is completely digital in that they convert both the analog input control signal and the analog actuator feedback signal into numerical values for the comparator to evaluate.

  According to one embodiment of the present invention, the servo motor 4 has a Hall effect servo motor feedback unit 5 that transmits information on the speed and direction of the rotor from the servo motor feedback unit 5 to the servo motor drive 6B.

  The principles and operation of a built-in, energy efficient hydraulic actuator system in accordance with the present invention can be better understood with reference to FIGS. 1 and 2 and the accompanying description.

  FIG. 1 shows a controller unit 6 including a bidirectional hydraulic pump 1, a hydraulic cylinder 2, a solenoid valve 3, and a servo motor 4, all of which includes a control electronic circuit unit 6A and a servo drive unit 6B. 1 illustrates a self-contained and energy efficient hydraulic actuator system controlled by.

  The bidirectional hydraulic pump 1 has a first port 8 and a second port 9 and has the ability to pump fluid in either direction. The first port 8 is connected to the first hydraulic fluid line 10 and the second port 9 is connected to the second hydraulic fluid line 11, respectively. The first hydraulic fluid line 10 further communicates with the hydraulic cylinder 2 through the first cylinder port 12, and the second hydraulic fluid line 11 further communicates with the hydraulic cylinder 2 through the second cylinder port 13. The hydraulic cylinder 2 includes a piston 14 and a rod 15 attached to the piston 14, and the piston 14 divides the inside of the hydraulic cylinder 2 into a first chamber 20 and a second chamber 21. The first cylinder port 12 and the second cylinder port 13 are installed at opposite ends of the hydraulic cylinder 2, and the first cylinder port 12 is connected to the first chamber 20 and the second cylinder port. 13 are connected to the second chamber 21, respectively. When the bi-directional hydraulic pump 1 pumps hydraulic fluid from the second port 9, the hydraulic fluid moves through the second line 11 and the second cylinder port 13 to the second chamber 21, The piston 14 moves into the first chamber 20 (or towards the load). At the same time, the hydraulic fluid exits the first chamber 20, travels through the first cylinder port 12 and the first line 10, and enters the hydraulic pump 1 through the first port 8. When the bidirectional hydraulic pump 1 changes direction, hydraulic fluid is pumped out of the first port 8 and moves the piston 14 into the second chamber 21 to drive it. The bidirectional pump 1 controls the movement and position of the piston 14 by changing the pressure difference between the two sides of the piston 14. In one of the preferred embodiments, the bidirectional hydraulic pump 1 is a reversible gear pump. The hydraulic cylinder 2 uses a double rod end type piston 14 to provide an equal annular area on both sides of the piston 14 and an equal volume when the piston 14 moves in either direction in the hydraulic cylinder 2 It is also preferable to maintain

  Servo motor 4 is liquid-free for this application due to the ability of servo motor 4 to reverse direction, change speed, and maintain a constant RPM quickly and continuously without duty cycle limitation. It is ideally suited for controlling a pressure pump (bidirectional pump) 1. In this way, the servo motor 4 can realize unrestricted start / stop and acceleration / deceleration (modulation duty) functions, for example, without the downtime required by induction motors with duty cycle limitations.

  Servo motor capabilities are critical to the claimed invention. This is because it allows controlled variable speed energy dissipation when the actuator operates. Therefore, it is serious to use the servo motor 4 configured to generate the rated torque of the maximum rated RPM from zero RPM under the load, and the servo drive unit 6B necessary to operate the servo motor 4. is there. The servo motor 4 has a servo motor feedback unit 5. The servo motor feedback unit 5 provides feedback of the rotor speed and rotor direction via the digital encoder via a feedback signal 6C. 6B, which ensures accurate RPM control under variable load conditions. Specifically, based on the feedback signal 6C from the servo motor feedback unit 5, the servo drive unit 6B maintains the servo motor RPM under the situation where the load increases and the situation where the load exceeds, and the direction of the rotor And closed-loop control of rotor speed. In essence, the hydraulic pump 1 and the servo motor 4 in combination function as a directional servo valve for controlling fluid flow rate and direction, so that the combination eliminates the need for a servo valve. In one of the preferred embodiments, the servo motor 4 is an AC brushless permanent magnet motor.

  The hydraulic fluid pressure is controlled or limited by adjusting the power input to the bi-directional hydraulic pump 1 via the servo motor 4, which requires the need for either a mechanical pressure regulator or an accumulator. Disappear.

  The solenoid valve 3 is configured to control fluid communication between the hydraulic cylinder 2 and the bidirectional hydraulic pump 1.

  By using the solenoid valve 3, it is possible for the actuator system to hold the load in place without operation of the servo motor 4 and not to operate the servo motor 4 to maintain the position of the actuator. become. Such capability minimizes energy consumption and extends the life of the servo motor 4 and the bidirectional hydraulic pump 1.

  This hydraulic actuator system also has the capability of dual mode operation, allowing the actuator to hold position with respect to the load with or without the solenoid valve 3. . In the first mode, the positions of the pistons 15 and 22 are held by a hydraulic lock generated in the hydraulic cylinder 2 when the solenoid valve 3 is closed. In operation in the second mode, the pistons 15 and 22 are held by controlling the speeds of the servo motor 4 and the bidirectional hydraulic pump 1. Servo motor 4 and hydraulic pump 1 rotate only at the speed necessary to push away internal leakage of hydraulic pump 1 and are required to maintain position with zero fluid flow with hydraulic cylinder 2 Maintain accurate pressure. The frequency response and position adjustment accuracy are not limited by the response time of the solenoid valve 3 and the minimum fluid flow for each response.

  The actuator system further includes a controller unit 6 including a control electronic circuit unit 6A. As used herein, the control electronics unit 6A starts and stops the servo motor, selects forward or reverse rotation, selects and adjusts speed, adjusts or limits torque, overload and Manual or automatic means for protecting against failure can be included.

  The controller unit 6 (including the control electronic circuit unit 6A and the servo drive unit 6B) receives the piston sensor feedback signal 22A from the position sensor 22 of the hydraulic cylinder 2 and supplies the control electronic circuit signal 6D to the solenoid valve 3. The control electronic circuit signal 6C is transmitted to and / or received from the servo motor feedback unit 5. Thus, the controller unit 6 has the ability to operate both the servo motor 4 and the solenoid valve 3 simultaneously so that the servo motor 4 and the solenoid valve 3 start / stop and open / close, respectively.

  The control electronic circuit unit 6A of the controller unit 6 closes the solenoid valve 3 and stops the servo motor 4 at the same time (within milliseconds), or almost simultaneously opens the solenoid valve 3 and loads the servo motor 4 under load. It can be programmed to generate a rated torque of maximum rated RPM from zero RPM. The control electronic circuit unit 6A also has the ability to receive a position sensor feedback signal 22A from a position sensor 22 attached to the hydraulic cylinder 2, and detects the position of the piston 14 / rod 15 and / or the hydraulic cylinder 2. Thus, the control electronic circuit unit 6A can control the direction and speed of the servo motor 4 by transmitting a control electronic circuit signal to the servo drive unit 6B. Thus, the servo motor 4 and the bidirectional hydraulic pump 1 are started in a few milliseconds before the solenoid valve 3 is actuated / opened. This timing and ordering are performed so that the pressure on the rear side of the solenoid valve 3 is equal to that on the load side so that there is no instantaneous reverse movement. In short, the servo motor 4 starts to pressure in a fraction of a second before the solenoid valve 3 opens, thus avoiding the first instantaneous drop in hydraulic pressure in the system.

  A hydraulic fluid reservoir 7 is preferred but not essential. In use, the hydraulic fluid reservoir 7 is sealed and has only the volume necessary to make up for volume changes due to hydraulic fluid and thermal expansion and contraction of the system. When the actuator system operates, fluid is not pumped into or out of the reservoir 7 but is simply pumped from one side of the hydraulic cylinder 2 to the other. The sealed hydraulic actuator system eliminates all external sources of fluid contamination, thereby minimizing the need to periodically change the fluid.

  FIG. 2 includes a bidirectional hydraulic pump 1, a hydraulic cylinder 2, solenoid valves 3, 3 ′, 3 ″, and a servo motor 4, all of which include a control electronic circuit unit 6A and a servo drive. FIG. 4 provides a schematic diagram of another preferred embodiment of a self-contained, energy efficient hydraulic actuator system controlled by a controller unit 6 comprising a unit 6B. FIG. 2 also provides a backflow prevention valve with a suction backflow prevention valve 26 that is used to maintain internal hydraulic fluid pressure inside the actuator system. As shown in FIG. 2, backflow prevention valves 26 'and 26 "can be used to prevent backflow through the filter F1. Similarly, other backflow prevention valves can be used to prevent backflow through the filter F2.

  As described above, the servo motor 4 has the servo motor feedback unit 5, and the servo motor feedback unit 5 sends the rotor speed and position feedback signal 6 C via the digital encoder to the servo drive of the controller unit 6. Provided to unit 6B, which ensures accurate RPM control under variable load conditions. Specifically, based on the position feedback signal 6C from the servo motor feedback unit 5, the servo drive unit 6B maintains the motor RPM under the situation where the load increases and the situation where the load exceeds, and the rotor RPM Achieves closed-loop control of position and velocity.

  The solenoid valve 3 is configured to control fluid communication between the hydraulic cylinder 2 and the hydraulic pump (bidirectional pump) 1. As described above, the control electronic circuit unit 6A has the ability to operate both the servo motor 4 and the solenoid valve 3 so that the servo motor 4 and the solenoid valve 3 are started / stopped and opened / closed, respectively. FIG. 2 also shows a preferred but not required hydraulic fluid reservoir 7.

  FIG. 2 also shows a second solenoid valve 3 ′ that can be added to the other end of the hydraulic cylinder 2 to maintain the pressure inside the hydraulic cylinder 2. A third solenoid valve 3 '' can also be used to introduce an emergency stop loop. Under an emergency condition, the solenoid valve 3 ″ opens and the hydraulic fluid bypasses the hydraulic pump 1 and the solenoid valves 3, 3 ″ so that one side of the hydraulic cylinder 2 (ie the second chamber) 21) directly moves to the other side of the hydraulic cylinder 2 (ie the first chamber 20). The solenoid valves 3, 3 ′, and 3 ″ receive a control electronic circuit signal from the control electronic circuit unit 6 </ b> A indicated by a dotted line 6 </ b> D in FIG. 2. The solenoid valve 3 ″ may also be in communication with the first line 10 and the second line 11 with a thick dotted line for emergency stop (ESD).

  The self-contained, energy efficient hydraulic actuator system 100 integrates all components together and is mounted as a unit on a device or valve that requires mechanical motion. The self-contained and energy efficient hydraulic actuator system 100 can also be designed as a modular unit and can be assembled from standard subassemblies, and the finished version of the actuator will meet the force and speed requirements of the application. To meet this, it is generated by selecting a suitable power unit and hydraulic cylinder 2.

  The energy efficiency of the presently claimed actuator system is compared to prior art systems in the following exemplary prediction example.

  When comparing the energy consumption between the claimed actuator system and the prior art actuator system, a number of variables must be considered in both the actuator design and its application. The efficiency of the motor, and hence the actuator, is highly dependent on the load and the speed at which the motor operates. In order to account for these many variables between the example systems, the following considerations were included in the calculation of energy consumption. 50% actuator motion duty cycle, i.e., the actuator moves 50% of the calculated period and rests 50%. When the actuator is operating or moving, the actuator is operating at full load and steady load, or its prime mover (motor) is generating its rated output or horsepower. The embodiment is based on an operational schedule of 24 hours a day, 7 days a week, and a year. The servo motor efficiency of Example 1 at all outputs is equal to 85%. Examples 2 and 3 have AC induction motors with an efficiency of 80% full power (rated RPM), and at 1/4 of the rated RPM, the efficiency of those AC induction motors is 75%. . The system of Example 3 operates at 100% RPM with varying load, such as 100% load when the actuator is moving, 20% load when at rest, and 70% motor efficiency at 20% load. The system of Example 2 operates the motor continuously at a changing RPM, such as 100% RPM while the actuator is moving and 25% motor RPM when the actuator is stationary.

  Examples 1 to 3 operate at the same voltage, 220 VAC, 3 phases, 1 hp is equal to 745 watts and the consumed power is kilowatt hours (kWh).

  The power used by the control electronics has been removed from all three embodiments on the principle that they all consume approximately the same amount of power. All three embodiments have the same motor hp output for all actuators based on the same load.

Example 1: Based on power usage in watts of the actuator system of the present invention.
(1.5hp / 0.85 efficiency) x (745w / hp) = 1,314 Watts
(1,314 Watts) x (365 days) x (24 hours) / 1000 = 11,510kWh
11,510kWh / 50% = 5,755kWh / year

Example 2: Based on the power usage in watts of the actuator system presented in published US Patent Application No. 2007/0101711.
(1.5hp / 0.80 efficiency) x (745w / hp) = 1,396 Watts
(1,396 watts) x (365 days) x (24 hours) / 1000 (0.5 on hours) = 6,114 kWh
+ (1.5hp / 0.75 efficiency) x (745w / hp) x ((365 days) x (24 hours) / 1000) x (0.5 off time)
= 12,640kWh / year

Example 3: Based on the power usage in watts of the actuator system presented in US Pat. No. 7,640,736.
(1.5hp / 0.80 efficiency) x (745w / hp) = 1,396 Watts
((1,396 watts) x (365 days) x (24 hours)) / (1000x (0.5 on hours)) = 6,114 kWh
+ ((1.5hp / 0.70 efficiency) x (745w / hp) x ((365 days) x (24 hours)) / 1000) x (0.5 off time)
= 13,106kWh / year

  In order to compare true energy consumption, the examples were prepared with the understanding that the data came from actual installations in comparable situations. However, great efficiency is the ability of the actuator system of the present invention to shut off the motor when the actuator is not moving. As presented in Example 1, the power usage of the presently claimed actuator system allows for significant energy efficiency over time. Surprisingly, Example 1 achieves more than 50 percent reduction in power usage over the calculated period.

  This description has not attempted to exhaustively enumerate all possible variations. That alternative embodiments could not be presented for a particular part of the invention and that alternative embodiments may result from different combinations of the parts described, or other alternative embodiments not described for parts What may be usable should not be considered a waiver of those alternative embodiments. It will be understood that many of those undescribed embodiments are within the literal scope of the following claims, and others are equivalent.

Claims (25)

At least one piston;
At least one bi-directional hydraulic pump in fluid communication with the piston for providing hydraulic fluid to the piston and controlling the position of the piston, comprising at least one hydraulic fluid inlet and at least one hydraulic pressure; A pump having a fluid outlet;
A servo motor operably connected to the pump to drive the pump;
At least one solenoid valve configured to control the hydraulic fluid between the piston and the bidirectional pump;
A controller for controlling the solenoid valve and the servo motor,
A hydraulic actuator system capable of maintaining the position of the piston when the servo motor is not driving the pump.   The system of claim 1, wherein the controller comprises a control electronics unit and a servo drive unit.   The system of claim 1, wherein the servomotor is capable of accelerating from zero to maximum revolutions per minute (RPM) under full load.   The system of claim 3, wherein the servomotor does not use energy at zero RPM.   The system of claim 1, wherein the controller can open a solenoid valve and start a servo motor substantially simultaneously, or close the solenoid valve and stop the servo motor.   The system of claim 1, wherein the piston is stored in a hydraulic cylinder.   The system of claim 1, wherein the piston comprises at least one rod.   The system of claim 1, wherein the solenoid valve is configured to hold a load without operating a servo motor.   The system of claim 1, wherein the servo motor comprises a servo motor feedback unit.   The system of claim 1, wherein the servo motor is an AC brushless permanent magnet motor.   The system of claim 6, wherein the hydraulic cylinder has a position sensor.   The system of claim 6, wherein the hydraulic cylinder comprises first and second chambers.   The system of claim 1, wherein the pump is in fluid communication with the piston by a first hydraulic fluid line and a second hydraulic fluid line.   The system of claim 6, wherein the hydraulic cylinder comprises a first cylinder port and a second cylinder port.   The system of claim 11, wherein the controller is configured to simultaneously receive signals from the sensor and servo motor feedback unit and send control signals to the servo motor and solenoid valve.   The system of claim 15, wherein the controller is configured to receive a feedback signal from the servo motor and the solenoid valve.   The system of claim 1, further comprising a sealed reservoir configured to compensate for volume changes due to hydraulic fluid and thermal expansion and contraction of the system.   The system of claim 1, wherein the servo motor has a torque of about 0.1 to about 2.0 horsepower, a torque of about 3 to about 28 inch-pounds, and a maximum RPM of about 4000 to about 5000.   The system of claim 1, wherein the bidirectional hydraulic pump has a displacement of about 0.0080 to about 0.08 cubic inches per revolution.   The system of claim 1, further comprising at least one suction backflow prevention valve and at least one filter.   A method for reducing energy consumption of a hydraulic actuator system comprising a servo motor and at least one solenoid valve, the controller receiving an input signal corresponding to a desired operation of the function of the system; The method includes: determining an operating limit by: and simultaneously controlling a servo motor and at least one solenoid valve of the hydraulic actuator system of claim 1. A method for reducing the energy consumption of a hydraulic actuator system, comprising:
(I) receiving at the controller an input signal corresponding to a desired operation of the function of the system;
(Ii) determining an operational limit for the system by the controller;
(Iii) simultaneously controlling a servo motor and a solenoid valve at the operating limit;
The hydraulic actuator system is at least one piston and at least one bi-directional hydraulic pump in fluid communication with the piston to provide hydraulic fluid to the piston and to control the position of the piston; A pump having at least one hydraulic fluid inlet and at least one hydraulic fluid outlet; a servomotor operably connected to the pump for driving the pump; and between the piston and the bidirectional pump And at least one solenoid valve configured to control the hydraulic fluid, wherein the controller controls the solenoid valve and a servo motor, and the piston when the servo motor is not driving the pump. The method can be maintained.   23. The method of claim 22, wherein the servo motor is capable of accelerating from zero to maximum revolutions per minute (RPM) under full load.   24. The system of claim 23, wherein the servomotor does not use energy at zero RPM. 23. The system of claim 22, wherein the controller can open a solenoid valve and start a servo motor substantially simultaneously, or close the solenoid valve and stop the servo motor.